The invention relates to image transfer, and more particularly, to the synchronization of transfers of images to copy sheets to reduce shutdowns.
For reliable and rapid movement of copy sheets through a reproduction machine, it is important to synchronize various drives and transports. This is important, in particular, in multi-drive machines such as in color machines wherein efficient registration and movement of sheets is essential to quality output. In addition, in an age demanding a variety of machine features and various machines to provide the features, the use of too many custom designed controls or other drives to provide the features creates an additional obstacle to consistent and reliable performance. For example, in a printing or reproduction machine, there are a variety of control profiles required for various applications such as driving the photoreceptor, driving a recirculating document handler or automatic document feeder, or driving copy sheets at various stages such as from the copy sheet source, to a registration gate, during a transfer operation, entering and exiting a fusing stations, and delivering copy sheets to many finishing stages such as to output trays, sorters, stackers, compilers, and staplers.
It is a generally known technique to provide controlled movement within positioning systems, in particular moving and registering paper within a xerographic reproduction or printing system. For example, U.S. Pat. No. 5,502,544, assigned to the same assignee as the present invention, discloses an imaging machine having a control and movable components including a photosensitive member and copy sheet transports. The control includes a servo system connected to given movable components and provided with control profiles for directing the movement of the component, including acceleration, deceleration, and constant velocity portions. A main controller monitors the operation and predetermined conditions and automatically changes selected portions of the control profile in response to predetermined conditions. In addition, U.S. Pat. No. 5,543,894, also assigned to the same assignee as the present invention, discloses a system for monitoring discrete drives at the time of transitions from one transport to another transport to detect mismatch and surface velocity. Upon detection of mismatch of velocity, a given controller is adjusted through a command bus to correct for the mismatch.
In the prior art, images from an image source are put into a marking subsystem at a constant speed. The paper handling subsystem delivers paper to the marking subsystem at a precisely specified time window in order to receive the image. The precise time of arrival is necessary because the arrival time determines the position that the image ends up on the paper. If the paper is delayed, the machine may be shut down because the image position would be outside the required position specifications. Further, as shown in U.S. Pat. No. 5,086,319 also assigned to the same assignee of the present invention, there is shown a system for automatically adjusting the velocity of a copy sheet to correct for previously determined misregistration of a document at an exposure station.
It would be desirable, however, if the paper handling system experienced a delay in transferring the paper to the marking subsystem, that the machine would be able to alter the marking system in order to match the time delay of the paper path. It would be desirable, therefore, to provide a control that uses bidirectional information feedback between marking and paper subsystems to accommodate paper path problems and registration problems. It is also desirable to provide a control wherein either the copy sheet can be selectively delayed or the marking system selectively rewrite an image, or both for suitable sheet registration.
It is an object, therefore, of the present invention to provide a new and improved control system wherein the marking system can be automatically altered. Another object of the present invention is to be able to change the control wherein either the copy sheet can be selectively delayed or the marking system selectively rewrite an image, or both for suitable sheet registration.
Other advantages of the present invention will become apparent as the following description proceeds, and the features characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.